A new paper authored by Anthony Watts, et al as part of the Berkley Earth Surface Temperature Project (BEST) (being submitted for publication) has now shown that the temperature guage site metadata (information about site changes like urban development, site moves, etc) used by NOAA and NASA's GHCN and resulting data adjustments overcompensated on high quality rural sites and undercompensated on poor quality urban sites, leading to overmodification of the temperature record, thus falsely showing a 0.308 C warming since 1979, when a new site rating methodology now shows the actual warming since 1979 has only been 0.15 C. Note the old, incorrect, exaggerated warming of 0.308 C has consistently been shown to be roughly half of the amount of warming predicted by the best computer climate models used by NOAA, NASA, and CRU to produce their predictions for the UN's IPCC report.

Anthony Watts, President, IntelliWeather, Chico, CA, USA

Evan Jones, IntelliWeather, Chico, CA, USA

Stephen McIntyre, Toronto, Canada

John R. Christy, Department of Atmospheric Science, University of Alabama, Huntsville, AL, USA

Call me (Richard Muller) a converted[fake] skeptic. Three years ago I identified problems in previous climate studies that, in my mind, threw doubt on the very existence of global warming. Last year, following an intensive research effort involving a dozen scientists, I concluded that global warming was real and that the prior estimates of the rate of warming were correct. I’m now going a step further: Humans are almost entirely the cause.

Let me [Richard Muller] be clear. My own reading of the literature and study of paleoclimate suggests strongly that carbon dioxide from burning of fossil fuels will prove to be the greatest pollutant of human history. It is likely to have severe and detrimental effects on global climate. I would love to believe that the results of Mann et al. are correct, and that the last few years have been the warmest in a millennium.

Love to believe? My own words make me shudder. They trigger my scientist's instinct for caution. When a conclusion is attractive, I am tempted to lower my standards, to do shoddy work. But that is not the way to truth. When the conclusions are attractive, we must be extra cautious.

It’s a scientist’s duty to be properly skeptical. I still find that much, if not most, of what is attributed to climate change is speculative, exaggerated or just plain wrong. I’ve analyzed some of the most alarmist claims, and my skepticism about them hasn’t changed.

Hurricane Katrina cannot be attributed to global warming. The number of hurricanes hitting the United States has been going down, not up; likewise for intense tornadoes. Polar bears aren’t dying from receding ice, and the Himalayan glaciers aren’t going to melt by 2035. And it’s possible that we are currently no warmer than we were a thousand years ago, during the “Medieval Warm Period” or “Medieval Optimum,” an interval of warm conditions known from historical records and indirect evidence like tree rings. And the recent warm spell in the United States happens to be more than offset by cooling elsewhere in the world, so its link to “global” warming is weaker than tenuous.

The careful analysis by our team is laid out in five scientific papers now online at BerkeleyEarth.org. That site also shows our chart of temperature from 1753 to the present, with its clear fingerprint of volcanoes and carbon dioxide, but containing no component that matches solar activity. Four of our papers have undergone extensive scrutiny by the scientific community, and the newest, a paper with the analysis of the human component, is now posted, along with the data and computer programs used. Such transparency is the heart of the scientific method; if you find our conclusions implausible, tell us of any errors of data or analysis.

What about the future? As carbon dioxide emissions increase, the temperature should continue to rise. I expect the rate of warming to proceed at a steady pace, about one and a half degrees over land in the next 50 years, less if the oceans are included. But if China continues its rapid economic growth (it has averaged 10 percent per year over the last 20 years) and its vast use of coal (it typically adds one new gigawatt per month), then that same warming could take place in less than 20 years.